1. Field of the Invention
This invention relates to novel cyclopropanes and polymers-derived therefrom, as well as a process for manufacture of the cyclopropanes and a process for manufacture of the polymers.
2. Brief Description of Prior Art
Advanced composite materials are made from combinations of high performance fibers, such as glass, graphite, carbon, silicon carbide or ceramic fibers, arranged in close packed alignment in the polymer as a matrix. Such composite materials provide a combination of strength and modulus superior to that of structural metals and alloys on an equal weight basis. Such composites are, for example, employed in military and commercial aircraft, and space vehicles, as well as in sports equipment, in tennis racquets, shafts for golf clubs and sailboats.
These composite materials are expensive, and so their use is confined to relatively high cost items. On the other hand, even though the raw materials for these advanced composites are expensive, over 70% of the costs associated with such composites result from the processing costs for their manufacture.
In particular, the currently used manufacturing processes produce volatiles during curing of the polymer matrix and such volatiles produce voids in the matrix which act as sites for structural failure. In order to minimize void formation during evolution of volatiles, the cure must be carried out over a long period, under reduced pressure and this manufacturing requirement is a major factor in the production cost.
Cross-linkable polymers are an important class of materials used in fiber reinforced plastics, thermosetting molding compounds, elastomers, coatings, adhesives, ion exchange resins, matrix resins for advanced composites and many other applications. A great deal of effort has been expended on the introduction of reactive functionality into polymers which will act as sites for cross-linking the polymers when heated.
The largest effort has been centered on the synthesis of polymers which contain terminal reactive groups such as acetylene containing moieties. Generally this involves the preparation of oligomers with reactive end groups which can subsequently be thermally chain extended to produce a highly cross-linked polymer matrix. Polymers containing reactive pendent groups have also been synthesized and these polymers have been thermally cured. Polymers containing internal reactive groups, have been less studied. High temperature cross-linkable polymers containing reactive groups such as acetylene, benzocyclobutene, ethylene and epoxide have been investigated, as described in U.S. Pat. No. 5,223,046, Hay et al.